Process and Assembly for Simultaneously Evaluating a Plurality of Catalysts

ABSTRACT

A process and an assembly for simultaneously evaluating a plurality of catalysts is provided wherein the flow rate of a reactive fluid to each of a plurality of reactors is automatically adjusted based on the measured amount of catalyst sample in each reactor to concurrently obtain a substantially identical fluid space velocity in each of the reactors.

CROSS REFERENCE TO RELATED APPLICATION

This application is a Continuation-In-Part of copending application Ser.No. 10/336,907 filed Jan. 6, 2003, the contents of which are herebyincorporated by reference in its entirety.

FIELD OF THE INVENTION

This invention relates generally to the testing and evaluation ofcatalyst materials and, more particularly, to a process and assembly forsimultaneously evaluating a plurality of catalysts.

BACKGROUND OF THE INVENTION

When formulating new catalysts, a large number of candidate catalystcompositions are typically synthesized. It then becomes important toevaluate the various candidate catalysts to determine and identify thoseformulations that are the most successful in catalyzing a particularlydesired reaction under a selected set of reaction conditions. Activityand selectivity are two key characteristics of a catalyst that arecommonly determinative of the success or desirability of the catalyst.The term “activity” commonly refers to the rate of conversion ofreactants by a given amount of catalyst under specified conditions. Theterm “selectivity” commonly refers to the degree to which a givencatalyst favors one reaction compared with other possible reactions.From the activity and selectivity values for a given catalyst, yieldsmay be calculated. Thus, it is typically advantageous to evaluate orcompare the performance of various catalyst materials based on theactivity, selectivity and/or yield achieved with the various catalystmaterials.

Traditionally, the activity, selectivity, and yield performance of acatalyst have been evaluated using a sequential approach. In such anapproach, each catalyst sample or candidate is typically independentlyserially tested in a selected reactor at one or more sets of specifiedreaction conditions. In practice, suitable test reactors for particularapplications may take various forms such as micro, pilot, bench-top andlab-scale reactors, for example. In most cases, such a test reactor isoperated in a fixed bed mode. Alternatively, when the ultimateenvisioned end use of a catalyst is in a fluidized bed application,catalyst samples may be tested using a test reactor operated in afluidized bed mode. After completion of the tests at one or more sets ofconditions, the tested catalyst sample is typically removed from thetest reactor and the next catalyst sample is loaded into the respectivereactor. The testing is then repeated on the freshly loaded catalystsample. The process is repeated sequentially for each of the desiredcatalyst formulations. As will be appreciated, the application of such aprocess to the testing of numerous various catalyst formulations can beundesirably time-consuming.

Developments in combinatorial chemistry were at first largelyconcentrated on the synthesis of chemical compounds. Recently,combinatorial approaches have been applied to the testing of catalystsin an effort to expedite the catalyst evaluation process. The use ofcombinatorial approaches to catalyst evaluation has, however, beengenerally limited or restricted such as due to difficulties or aninability of ensuring the generation of a self-consistent combinatorialdata set. In particular, combinatorial testing in which library membersare evaluated at different space velocities typically results in datasets which are not self-consistent, e.g., performance differences may beat least in part attributable to differences in space velocities ratherthan to differences in the formulation of the various catalyst samples.For example, because a combinatorial approach commonly involves theloading of many samples for each run, the process of individuallymeasuring out a specified weight for each sample can become extremelyburdensome. Moreover, because combinatorial synthesis generally producesor results in a wide variety of materials such as may have widelyvarying properties, such as density, even reactors wherein materialshave been loaded in a constant volume manner may contain significantlyvarying weights of material.

In view thereof, there is a need and a demand for proceduraldevelopments in combinatorial catalyst evaluation such as to betterensure self-consistent data sets such as by permitting or facilitatingevaluation or comparison of each of multiple catalyst samples at asubstantially identical space velocity. Further, there is a need and ademand for an assembly which facilitates and permits the generation of aself-consistent catalyst evaluation data set such as wherein each ofmultiple catalyst samples is concurrently evaluated at a substantiallyidentical space velocity.

SUMMARY OF THE INVENTION

A general object of the invention is to provide an improved process andassembly for simultaneously evaluating a plurality of catalysts.

A more specific objective of the invention is to overcome one or more ofthe problems described above.

The general object of the invention can be attained, at least in part,through a process for evaluating a plurality of catalyst samples forcatalysis of at least a portion of a fluid. In accordance with onepreferred embodiment of the invention, such a process involves formingan array of a plurality of parallel reactors wherein each of thereactors contains a measured amount of at least one of the plurality ofcatalyst samples. A quantity of the fluid is passed to each of thereactors at a flow rate automatically adjusted based on the measuredamount of the at least one of the plurality of catalyst samples in eachreactor to concurrently obtain a substantially identical first spacevelocity in each of the reactors.

The invention further comprises an assembly for evaluating a pluralityof catalyst samples for catalysis of at least a portion of a fluidwherein a measured amount of catalyst sample is disposed in each of anarray of N parallel reactors. In accordance with one preferredembodiment of the invention, such an assembly includes at least N fluidflow regulators and a control unit in operational communication with theat least N fluid flow regulators. Each regulator is in fluid flowregulation communication with a corresponding one of the parallelreactors and is effective to regulate a rate of flow of the fluid to thecorresponding one of the parallel reactors. The control unit iseffective to automatically adjust the rate of flow of the fluid to thecorresponding reactor based upon the measured amount of catalyst in thereactor, to concurrently obtain a substantially identical first spacevelocity in each of the reactors.

The prior art generally fails to provide processes and assemblies forthe evaluation of a plurality of catalysts in a manner which is aseffective as may be desired. In particular, the prior art generallyfails to provide processes and assemblies conducive to a greater or morewidespread use of combinatorial approaches to catalyst evaluation asprior combinatorial approaches to catalyst evaluation have typicallybeen limited or restricted due to a difficulty or an inability ofensuring the generation of a self-consistent combinatorial data set.

As used herein and as identified above, references to catalyst“activity” generally refer to the rate of conversion of reactants by agiven amount of catalyst under specified conditions and references tocatalyst “selectivity” generally refer to the degree to which a givencatalyst favors one reaction compared with another possible reaction.

References herein to space velocities as being “substantially identical”are to be understood to generally refer to space velocities that differfrom one another by no more than about ±10% and, more preferably, differfrom one another by no more than about ±6%.

“Weight Hourly Space Velocity”, sometimes abbreviated as “WHSV”,generally refers to the mass flow rate of total feedstock or selectedfeed component per mass of loaded catalyst, with units of inverse time,e.g., hr⁻¹.

“Liquid Hourly Space Velocity”, sometimes abbreviated as “LHSV”,generally refers to the volumetric flow rate of total feedstock orselected feed component (typically expressed at a reference temperature)per volume of loaded catalyst, with units of inverse time, e.g., hr⁻¹.

Other objects and advantages will be apparent to those skilled in theart from the following detailed description taken in conjunction withthe appended claims and drawing.

BRIEF DESCRIPTION OF THE DRAWING

The FIGURE is a simplified schematic of an assembly for evaluating aplurality of catalyst samples in accordance with one preferredembodiment of the invention. The FIGURE illustrates only one of multiplebanks of reactors.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides an improved process and assembly forsimultaneously evaluating a plurality of catalysts.

In general terms, the present invention applies a combinatorial approachfor simultaneously testing a plurality of catalyst samples. As describedin greater detail below, the invention provides an approach that israpid and yet provides an accurate basis for comparison of catalystperformance characteristics determined for each of a plurality ofcatalyst samples. The plurality of catalyst samples used in the practiceof the invention may be any number beginning with at least two.Different catalyst samples may be of the same or a differentformulation, or the same formulations may be present in different ratiosof a mixture. Furthermore, identical catalyst sample formulations ormixtures may be repeated within the plurality, especially such as whenstatistical analysis are being conducted.

In accordance with the invention, an array of a plurality of parallelreactors is formed wherein each of the plurality of reactors contains ameasured amount of at least one of the plurality of catalyst samples.The array of parallel reactors may be as few as two reactors, butpreferably contains 6, 8, 12, 24, 48, 96, 384, or 1264 reactors. It isgenerally preferred that the array of parallel reactors be arranged in arow and column formation similar to that of a microtiter tray.

A common objective of catalyst evaluation testing is to produce orprovide a comparison of yields, such as calculated from the activity andselectivity, based on the use of each of a plurality of catalyst samplesin order to determine which catalyst sample is most suitable for use inconnection with a given reaction. As identified above, to facilitatecomparisons of yield, activity, and/or selectivity for various catalystsamples in a plurality, it is desirable that there exist a common basisfor comparison. The present invention provides such a common basis forcomparison for different catalyst samples by automatically adjusting theflow rate of fluid to each of the plurality of reactors based on themeasured amount of the catalyst sample in each reactor to concurrentlyobtain a substantially identical fluid space velocity in each of thereactors.

Catalyst activity and/or selectivity may be determined fromcompositional analysis of each of the effluents (discussed in detailbelow), and the percent yield in each of the reactors of the array maybe calculated. It is preferred to compare the percent yield of thecatalyst samples to determine which of the catalyst samples exhibits themost preferred performance.

Those skilled in the art and guided by the teachings herein providedwill appreciate that the broader practice of the invention is notnecessarily limited by or to the mode of operation of the catalyst bedreactors employed in the practice of the invention. Thus, it will beunderstood that the invention can, if desired, be practice employingfixed or fluid bed reactors, as may be desired for specificapplications. It is currently generally believed preferred that theinvention be practiced employing or utilizing fixed bed reactors. Inparticular, fixed bed operation may generally be found easier to run asin typical fluidized bed operations the catalyst materials are generallyonly fluidized over a limited range of catalyst masses, particle sizesand flow rates whereas fixed bed operations generally do have suchlimitations. Furthermore, fixed bed operations can avoid difficultiesthat may be encountered with simulating fluidized bed hydrodynamicbehavior on a micro-combinatorial scale as well as facilitate a systemor assembly scale-up, such as may be desired for a commercial operation.

A fluid feed including one or more reactants is introduced to thecatalyst bed reactor such as by any commonly known manner. The term“reactants” is sometimes used in the description of the process of theinvention, but it should be understood that many chemical reactionsrequire only a single reactant and the use of the plural form of theword reactant is for ease of explanation and not meant to limit theinvention to only those reactions requiring more than one reactant.Thus, it is to be understood that the present invention can besuccessfully applied to chemical reactions having only one reactant aswell as those having two or more reactants.

Those skilled in the art and guided by the teachings herein providedwill also appreciate that the broader practice of the invention is notnecessarily limited by or to application with particular or specificreactant feed materials. Further, particular fluid feeds used in thepractice of the invention may additionally contain or include one ormore diluents, co-reactants or additives such as known to those skilledin the art and guided by the teachings herein provided. For example,suitable diluents useable in the practice of the invention may includeair, N₂, H₂, He, Ar; examples of suitable co-reactants useable in thepractice of the invention may include air, O₂, H₂O, H₂, N₂, C1 ₂ and NH₃and examples of suitable additives useable in the practice of theinvention include H₂O, NH₃, H₂S, CO, CO₂. It will be understood andappreciated by those skilled in the art and guided by the teachingherein provided that the particular classification of at least certainthese materials can differ based on the specifics or particulars of theoperation. Furthermore, the broader practice of the invention is notnecessarily limited to or by the classification of a particular addedfeed material as a diluent, co-reactant or additive, for example.

Furthermore, those skilled in the art and guided by the teaching hereinprovided will appreciate that the invention can be suitably applied tothe various reactions such as can be conducted in such reaction vesselssuch as, for example, including partial oxidations, CO and/or NO_(x)removals, chlorinations and aminations as well as heterogeneouscatalysis such as hydrocarbon conversions wherein a reactant feed iscomposed of one or more selected hydrocarbons and a co-reactant such ashydrogen, air or oxygen. Examples of hydrocarbons for which practice ofthe invention may have particular application include paraffins such aspropane, butanes, pentanes, hexanes and heptanes; aromatics such asbenzene, toluene, and xylenes; and naphthenes such as cyclopentanes andcylcohexanes. It is to be understood, however, that the broader practiceof the invention is not necessarily limited to or by operation withparticular hydrocarbons or the conversion thereof.

After introduction and contact with each of the respective catalystsamples, a reaction by or of the reactants may be catalyzed. Of course,since catalyst performance evaluation is a goal of the invention, it isexpected that some of the catalyst samples tested will not catalyze thereaction at all, or perhaps only very little.

When the reactants contact the catalyst sample beds, an effluent isformed. In an embodiment wherein each reactor contains a catalyst samplecomposed of different catalysts or blend of catalysts, it is expectedthat the effluent may vary considerably from catalyst sample to catalystsample. Consequently, some effluents may contain largely reactant orother fluid feed component, and other effluents may contain largelyproduct, with a wide variety of feed to product ratios therebetweenpossible.

The effluents may in turn be analyzed using at least one selectedanalytical technique to determine whether products have been formed, howmuch product has been formed, and/or which specific product compoundshave been formed. Those skilled in the art and guided by the teachingsherein provided will appreciate that various analytical techniques maybe used including any suitable technique for the type of informationdesired and components involved. In general, preferred techniquesinclude, chromatography, spectroscopy, and nuclear magnetic resonance.Various different forms of chromatography and/or spectroscopy may beemployed. Specific examples of chromatography and spectroscopy useablein the practice of the invention include liquid chromatography, gaschromatography, ultraviolet absorption spectroscopy, Raman spectroscopy,mass spectroscopy, visible absorption spectroscopy, ultraviolet-visiblespectroscopy, atomic absorption spectroscopy, infrared absorptionspectroscopy, and emission spectroscopy. While chromatography andspectroscopy methods are preferred, other acceptable techniques includebut are not limited to fluorescence spectrometry, mass spectrometry,X-ray methods, radiochemical methods, electroanalytical methods,potentiometric methods, conductometric methods, electrogravimetricmethods, coulometric methods, and voltammetry.

In accordance with one preferred embodiment of the invention, at least aportion of the effluent from each reactor is conveyed to the chosenanalytical instrument. The effluents may be directly conducted to ananalytical instrument, or aliquots of the effluents may be sampled anddelivered to the location of the analytical instrument. In yet anotherembodiment, the effluents may be analyzed on-stream as they are removedfrom the reactors. In evaluating catalyst performance, observing trendsof activity, selectivity, and yield over time can be valuable.Therefore, it may be desirable in particular applications that theeffluent that is being withdrawn from each reactor be periodically orcontinuously analyzed as discussed above. Selectivity, activity, and/oryield may be determined upon the occurrence of each analysis, and trendsin selectivity and/or activity observed over time. It is generallypreferred that the effluents of each of the reactors be sampledsimultaneously such that the analysis results are directly comparableand the time that each catalyst has been exposed to the reactant is thesame. For quantitative results, the amounts of the effluents analyzedare measured. Alternatively, the reactors can be started sequentially toaccount for the offset in analysis time.

The specific analysis performed will typically depend on the particularapplication and desired information. For example, if only the activitiesof a plurality of catalyst samples are to be determined and compared, aneffluent analysis measuring the amount of reactant consumed may besufficient. Also, a qualitative analysis for the composition of theeffluent can, if desired, be used as an indication of catalyst activity.However, it is generally preferred to have both activity and selectivityinformation and, in such instances, the analytical technique would beselected to measure the concentrations or quantities of the differentcomponents present in each effluent. Using information on both activityand selectivity, the yield of the desired products can be calculated andcompared between the individual catalyst samples. It is preferred thatthe sampling of the effluent for each reaction be conductedsimultaneously. A benefit of simultaneous sampling is that the resultsobtained for each catalyst bed are more readily comparable since eachcatalyst bed would have been exposed to the reactant for the same periodof time. This is perhaps best understood via a description of anexample. In a 48-reactor array with a single analyzer/detector, if thesampling of the 48 effluents were to occur sequentially, and the timeneeded for each sampling was one minute, there would be a 48 minutedifference in time between sampling of the first and the last of thereactors. Therefore, the overall time the last catalyst sample would beexposed to the reactant would be 48 minutes longer than the overall timethe first catalyst sample would be exposed to the reactant. It is knownthat the activity and selectivity of a catalyst may change over theperiod of time the catalyst is in use. Thus, during such a 48 minutetime period between the sampling of the first and the last of thereactors, the activity and/or selectivity of the catalyst in the lastreactor may have changed significantly as compared to that of thecatalyst in the first of the reactors. Thus, it is to be appreciatedthat sequential sampling has an increased likelihood of introducingerror since the period of time that a catalyst is in use, rather thanbeing identical for all reactors, could become another variable to beaccounted for in the analysis.

Turning to the FIGURE, there is illustrated a simplified schematic of anassembly, generally designated with the reference numeral 20, forevaluating a plurality of catalyst samples in accordance with onepreferred embodiment of the invention. For ease of explanation, theprocess and apparatus will be described herein in reference to a48-reactor system where the reactors are grouped into six banks, witheach bank containing eight reactors. The FIGURE shows only the firstbank of eight reactors. The other five banks of eight reactors each arenot shown.

As shown, a reactant-including fluid feed stream feed stream 22 feedsinto the assembly 20. The fluid feed is preferably gaseous but may be aliquid. The feed may be from cylinders and, if the feed is in the formof a gas, may be saturated with other components. In particularembodiments, the feed may be a liquid and such as processed through apump (e.g., a syringe).

The reactant-containing fluid feed stream feed stream 22 is separated,via respective branch connectors 24, into eight separate portions, eachdesignated by the reference numeral 25. The eight separated portions 25are not regulated as to flow at this point. As described in greaterdetail below, the eight separated portions 25 are employed to form eightcorresponding reactor feed streams individually designated 40, 42, 44,46, 48, 50, 52 and 54, respectively.

The eight separated portions 25 are each simultaneously conductedthrough a respective flow regulator or controller 58 to form the eightcorresponding reactor feed streams 40, 42, 44, 46, 48, 50, 52 and 54,respectively. Therefore, a set of eight flow controllers are used foreach of the six banks of reactors. As will be appreciated, the inventionadvantageously allows or permits flow control to be conductedcontinuously over a range of fluid flow rates in a manner not allowed orpermitted with systems which rely on the incorporation and use of fixedrestrictors.

As described in greater detail below, the flow regulators 58 are used toindividually regulate or control the flow rate of fluid feed in each ofthe reactor feed streams 40, 42, 44, 46, 48, 50, 52 and 54,respectively. Depending upon the application and the data desired orvariables being investigated, the set of feed streams may be regulatedor controlled to provide the same feed fluid flow to the reactors orthey may be controlled at different flows. Those skilled in the art andguided by the teachings herein provided will appreciate that such flowregulation or control may be done on the basis of or in the form ofgravimetric or volumetric flow regulation or control as may be desiredfor a particular application.

Each of the respective pressure transducers 60 monitors the pressure ofthe reactor feed in the respective feed line 40, 42, 44, 46, 48, 50, 52and 54. The respective reactor feed streams are individuallysimultaneously introduced to a corresponding associated individualreactor 26. The reactors 26 may be of any type used in combinatorialevaluations, with preferred reactors being of the type described in EP1108467 A2. As identified above, the number of reactors or vessels whichmake up the plurality may vary dependent upon the particular applicationand will typically vary between from two vessels to hundreds of reactorsor vessels. Banks of reactors have generally been constructed inmultiples of eight. Consequently, it is generally preferred to have atleast eight reactors or vessels in the plurality.

The reactors 26 each houses or contains a measured amount of at leastone of a plurality of catalyst samples. As identified above, each of thereactors may contain a catalyst sample composed of different catalystmaterials, different mixtures of catalyst materials, or, alternatively,the same compositional mixture of catalyst materials but where thecomponents are in different ratios, or the like. In addition, replicatecatalyst samples may be included within the array of the parallelreactors.

The system assembly 20 also includes a control unit 70 in operationalcommunication with the fluid flow regulators 58, as signified by thecontrol lines 72, and effective to automatically adjust the rate of flowof the fluid to the respective corresponding reactors 26 based on themeasured amount of catalyst in each reactor 26, to concurrently obtain asubstantially identical space velocity in each of the reactors 26. Aswill be appreciated, various control units such as known to thoseskilled in the art and guided by the teachings herein provided areuseable in the practice of the invention. Examples of such control unitsinclude LabVIEW, available from National Instruments Corp., HoneywellDCS (distributed control system) and ABB Siemens DSC, for example.Furthermore, in accordance with a preferred practice of the invention,such automatic adjustment of the rate of flow of the fluid to thereactors 26 can be preferably done continuously over a range of fluidflow rates such as to permit the obtaining of a substantially identicalspace velocity in each of the reactors without requiring that thereactors contain catalyst loads which are equal or differ from oneanother in any predetermined manner or by any discrete amount. As aresult, the invention provides great flexibility in testing conditionswhile also simplifying and facilitating the manner of securingself-consistent data sets such as may be desired and useful in catalystevaluations.

Control unit 70 is in operational communication via signal connectionline 82 with mass balance 80. Measured weights of catalyst may bedirectly transmitted to the control unit which automatically adjusts therate of flow of the fluid to the reactors 26. Mass balance 80 isoperated in conjunction with a volumetric loader 84 such as that foundin U.S. Pat. No. 6,817,558.

Those skilled in the art and guided by the teachings herein providedwill appreciate that the fluid flow rate can be adjusted on a mass basis(e.g., mass flow rate) or a volumetric basis (e.g., volume flow rate),as may be desired in particular applications.

The effluent from each of the reactors 26 is conducted simultaneously,yet separately, in lines 28 to a sampling system 30 in order to samplethe effluents for further processing such as analysis. The sampling ofthe effluent from each of the reactors 26 may be advantageouslyconducted simultaneously, as identified above. Alternatively, suchsampling can be conducted in a sequential manner, if preferred.

When the effluents are not actively being sampled, the respectiveeffluent can be conducted through an independent path, shown as thelines 32, to a proper venting system. As will be appreciated, dependenton the compounds employed and being treated in the system assembly 20,waste effluents may be treated to remove, convert or neutralize specificcompounds, components or materials before being vented to theatmosphere. For certain applications, the effluents may be condensed andcollected, such as for further use or disposal, as may be desired orappropriate therefor.

Joined to or connected with the sampling system 30 is a processing oranalytical device, designated by the reference numeral 33. A gaschromatograph is an example of one suitable common form or type ofanalytical device for use in particular applications of the invention.As will be appreciated, however, other suitable types or forms ofanalytical techniques such as described above may be used or employed inthe practice of the invention. Consequently, it is to be understood thatthe broader practice of the invention is not necessarily limited by orto operation with a specific or particular analytical technique orsampling procedure.

The analytical device 33 has an input or carrier stream 34 and ananalytical device effluent stream 36.

In addition, the reactors 26 may be, if desired and as shown, associatedwith a heater 41 having a controller 43 to provide controlled heat tothe reactors. Alternatively, individual heaters may be employed for eachor selected of the reactors 26.

It will further be appreciated by those skilled in the art and guided bythe teachings herein provided that the above described assembly 20 mayadditionally contain or include additional components or features suchas pressure transducers, check valves and pressure controllers, forexample, as may be desired in particular applications.

As identified above, each of the plurality of reactors contains ameasured amount of a catalyst sample. Those skilled in the art andguided by the teachings herein provided will appreciate that varioustechniques or means are available and may be used to provide or ensurethat a measured amount of catalyst sample is present in particularreactors of the plurality. For example, such measured amount of catalystsample can be of determined on a gravimetric or volumetric basis. Inaccordance with one preferred embodiment of the invention, suchgravimetric measurement may be via indirect weighing of the catalystsample such as by weighing a holder portion of the reactor of interestusing a mass balance, loading the catalyst sample into the weighedholder portion, followed by weighing the catalyst sample-loaded holderportion of the reactor of interest. As will be appreciated, such loadingof catalyst samples may be done on a volumetric basis, such as inaccordance with a preferred embodiment of the invention, via the loadingof catalyst samples of substantially identical volume into the variousof the plurality of reactors. In such indirect weighing of the catalystsample, the amount of the catalyst sample generally corresponds to thedifference between the weight of the catalyst sample-loaded holderportion and the weight of the empty holder portion. In accordance withanother preferred embodiment of the invention, such gravimetricmeasurement may be via direct weighing of the catalyst sample. Whenloading a substantially identical volume of catalyst into the pluralityof reactors, the weight of the catalyst may also be measured. Thebenefit of precision volumetric loading is to rapidly load catalyst inamounts that will be gravimetrically similar to one another. An exampleof a suitable device for precision volumetric loading is U.S. Pat. No.6,817,558 hereby incorporated by reference in its entirety.

In accordance with a preferred practice of the invention, the generationof a self-consistent catalyst evaluation data set is provided viaconcurrently evaluating each of the multiple catalyst samples at asubstantially identical space velocity based on at least one of thefluid feed components. As will be appreciated by those skilled in theart and guided by the teachings herein provided, such space velocitiesmay be determined on an appropriate selected basis such as a weighthourly space velocity or a liquid hourly space velocity, for example.Moreover, it is to be understood that while the broader practice of theinvention is not necessarily limited to application with specific orparticular space velocities, the invention is currently conceived asbeing particularly advantageous in applications wherein thesubstantially identical space velocity in each reactor of the array isin a range from about 0.1 to about 1000 hr⁻¹, with further specificembodiments having particular utility in applications wherein thesubstantially identical space velocity in each reactor of the array isin a range from about 300 to about 600 hr⁻¹ or, alternatively, in arange from about 1 to about 35 hr⁻¹. As will be appreciated, interest inparticular or specific range or ranges of space velocities willgenerally be dictated by catalyst chemistry and kinetics with particularemphasis on catalyst chemistry and kinetics that permit commerciallyamenable space velocities.

If desired and as may be preferred, one or more or, if desired, all ofthe catalyst-loaded reactors of the array may, after a period of time,be tested at a second selected substantially identical space velocitysuch as where the second substantially identical space velocity is thesame or different from the first substantially identical space velocityat which such catalyst-loaded reactors of the array were originally orpreviously tested. Furthermore, one or more or, if desired, all of thecatalyst-loaded reactors of such an array may, after a period of time,be tested at a third selected substantially identical space velocitysuch as where the third substantially identical space velocity is thesame or different from either or both the first and the secondsubstantially identical space velocity at which such catalyst-loadedreactors of the array were originally or previously tested.

Thus, the invention provides a process and an assembly forsimultaneously evaluating a plurality of catalysts at a substantiallyidentical space velocity such as to better permit the evaluation of suchcatalysts on the basis of self-consistent data sets.

It will be appreciated by those skilled in the art and guided by theteachings herein provided that while the invention has been describedabove making specific reference to an embodiment wherein a constant dataset is obtained via operation at substantially identical spacevelocities, the invention can, if desired, be practiced such that flowsare appropriately adjusted to obtain or result in substantiallyidentical conversions. Furthermore, a hybrid manner of testing oroperation such employing both constant space velocity and constant flowrate steps can, if desired, be employed.

Moreover, the method of the invention can, if desired, be repeated for apreviously tested catalyst sample at a space velocity that is the sameor differs from that at which the catalyst sample was previously tested.

The invention illustratively disclosed herein suitably may be practicedin the absence of any element, part, step, component, or ingredientwhich is not specifically disclosed herein.

While in the foregoing detailed description this invention has beendescribed in relation to certain preferred embodiments thereof, and manydetails have been set forth for purposes of illustration, it will beapparent to those skilled in the art that the invention is susceptibleto additional embodiments and that certain of the details describedherein can be varied considerably without departing from the basicprinciples of the invention.

1. An assembly for evaluating a plurality of catalyst samples forcatalysis of at least a portion of a fluid wherein a measured amount ofcatalyst sample is disposed in each of an array of N parallel reactors,the assembly comprising: at least N fluid flow regulators, eachregulator in fluid flow regulation communication with a correspondingone of the parallel reactors and effective to regulate a rate of flow ofthe fluid to the corresponding one of the parallel reactors; a massbalance; a control unit in operational communication with the at least Nfluid flow regulators and the mass balance, said control unit effectiveto automatically adjust the rate of flow of the fluid to thecorresponding reactors based upon the measured amount of catalyst ineach reactor, to concurrently obtain a substantially identical firstspace velocity in each of the reactors.
 2. The assembly of claim 1wherein the fluid flow regulators are mass flow regulators.
 3. Theassembly of claim 1 wherein the fluid flow regulators are volume flowregulators.
 4. The assembly of claim 1 wherein the reactors are fixedbed reactors.
 5. The assembly of claim 1 wherein the reactors arefluidized bed reactors.
 6. The assembly of claim 1 further comprising atleast N effluent conduits in fluid communication with a sampling system.7. The assembly of claim 6 further comprising at least one analytical orprocessing device in fluid communication with the sampling system. 8.The assembly of claim 1 further comprising at least one heaterassociated with at least the N parallel reactors.
 9. The assembly ofclaim 1 further comprising a volumetric loader associated with the massbalance.